Sealing plate for sand filter cleaners



YDec. 20, 1938. w c. LAUGHLIN 2,141,153

SEALING PLATE FOR SAND-FILTER QLEANERS Y Filed Oct. 6, 1937 ATTORNEY.

FCE

UNITED STATES., PAENT 21111.15?.v sEArQiNG'PLATnx-on SAND FILTER CLE l B5 William C. New Yorin, Y., assigner to Filtration Equipment Corwration, New Yorks; N. Y., a corporation of Delaware Application @canberra-1937, No. 167,(.525 5 claims.- (cl. zit-12s) This invention relates to cleaning mechanisms conjunction with which it may be used. The 'for sand lters, and more particularly to cleaninvention will be described with reference to the ing devices for clarication iilters of the type in operation of a lter of the downflowtype since which a relatively thin bed of sand is used as the leakage of wash water through' the cleaning area I filtering medium. The invention is particularly is more serious in this type o f iilter than in one 5 designed for use in conjunction with cleaning ofthe upflow type.

mechanisms for clarication filters of the down- 'Apreierred embodiment of the invention is illow type, 'althoughin its broader aspects it is lustrated in the accompanying drawing, in which not limited thereto. lt is shown as applied to a'caisson cleaner em.

l In cleaning sand lters and particularly clariploying an electromagnet as the agitating means, 3-

fcation filters employing -a relatively thin bed and in which of sand as the iiltering material, it is now. the Fig. l iS a plan VieW 0f a DOItiOn 0f a Caisson practice to provide traveling cleaners ofthe cleaner equipped with the sealing plate of the type which move continuously or intermittently present invention, the superstructure being -cut l over the filter bed.v Such cleaners are provided away aS indicated by the line l-l of Fig. 2`and a 15.-'

with agitators for creating a localized. area. of part of the solenoid being broken Way t0 ShOW agitation in the sand of the lter in order to the sealing plate. release the dirt and accumulated impurities Fig. 2 is a vertical section on the line 2-2 of therefrom. The dirt so released is taken up by Fig. 1, showing the cleaner as applied to a clariastream of water, known as wash water,whlch fication sand filter of the downilow type, and 20 passes into a chamber in the cleaner from which Fig- 3 iS a lrigitildirlal SeCtiOIl 0n the line 3-3 it is preferably continuously discharged by a of Fig. 1. pump. l The caisson cleaner illustrated in the draw- 'I'here are a number of known cleaning devices lng 'is essentially the same as that described of the above nature which are now used for in the Laughlin et al. Patent No. 1,872,759, and 25 clarification iilters, some of which operate merely Only S0 much 0f the Structure 0f the Cleaning by mechanical agitation of the sand, others by the mechanism is shown as cooperates with the seal- 1 injection of jets of water into the sand, and still ins plate cf the present invention The, lter i1- others by the agitation of magnetite sand or luStrated iS. however, a ilOWIlilOW illtel instead other magnetic material by means of an interof the upilow iilter illustrated in thisA patent. 30 mittently operating electromagnet. However, Referring to the drawing, the filter indicated all the cleaning devices of which I am aware generally by the reference numeral I includes a operate upon the principle of agltating successive filter Canal 2 0f Concrete Orv Other Suitable maportions of the lter bed and withdrawing acterial, which may be mounted in or around the cumulated impurities therefrom in the form of periphery of a rectangular 0r circular settling 35 a water suspension, and it is an object of my intank or which may be entirely Separate and revention to improve the effectiveness of any cleanmoved Seme distance therefrom. A filter bed er 0f this type by sealing off the area directly support 3 in the form of a rigid bronze grid or the under the agitator, as will be explained. A furlike is a'ixed to the walls of the filter canal 2 40 ther object resides in the provision of a sealing some distance above the bottom, thereby dividing 40 plate adapted to travel beneath the surface of the canal into an upper influent passage 4 and the sand of the filter directly under the area a lower eilluent passage 5 Liquid inlets and of agitation to baille the flow' of water thereoutlets (not shown) are provided in the inlet and through and cause it to be dispersed laterally outlet passages il and 5 respectively, and the outintothe sand of the illter. Other objects of the let passage may be Provided With a COHtIOl Weir 45 invention will be apparent from the following Capable 0f raising the level 0f the liquid therein description when taken with the claims appended above the level of the iilter bed as described in hereto. greater detail in my Patent No. 1,975,109.

The invention will be illustrated in greater de- Supported 0n the grid 3 is a fine screen B'cf tail by describing a preferred modiflcation therecopper or bronze, and on this screen is a'iilter 50 of as applied to the type of filter and cleaning bed 1. of sand which is preferably of 10-40 mesh mechanism which is described in the Laughlin et in size. In the modification shown, this sand is al. Patent No. 1,872,759, but it should be undera magnetic sand of menetite or other material stood that this description is merely representa-V capable of being attracted by an electromagnet, tive of one of a number of cleaning devices in although it may consist of ordinary quartz sand 55 I hydraulic agitator.

-into an outflow channel.

when other types of agitators are used. The layer of said constituting the filter bed is relatively thin, in order to permit rapid filtration, and is generally of the order of 6-8 inches in thickness.

The cleaning device I0 consistsgenerally of a caisson or cleaner tank H, which is made up of side walls I2 and end walls I3 and which is open at its top and bottom. l'The rear wall I3 is preferably attached to a bottom plate I4 which extends across the full width of the caisson between the side walls I2, and the forward end thereof is preferably bent upwardly as at I5 to form a chamber .I6 for the reception of wash water. Within this chamber is a pump I'Sa forV discharging the wash water therefrom. The effective water level in the chamber I5 is determined by an adjustable weir plate` I1, which is adjustably attached to the uper edge of the plate I5 as by nuts and bolts I8. A vertical baille I9 fits across the upper part of the caisson between the side Walls I2 and slightly in advance of the Weir plate II in order to form a restricted neck or inlet 20 and to prevent the entrance of sand from the lter into the chamber I6.

The caisson is provided with an agitator in the form of an electromagnet 2I, in conjunction with which the sealing plate of the present invention is adapted to operate. In its most em'- cient form the electromagnet 2I has an open core 22, since the path of greatest magnetic permeability should extend through'the material of the -lter bed rather than through a soft iron cor'e. The electromagnet or solenoid 2| is supported by cross bars 23 which are attached to angle irons 24 on top of the caisson by means of threaded rods 25 which are so adjusted that the magnet isjust above the lter bed.

The cleaning mechanism which has been described is also described in greater detail and claimed in the Laughlin et al. Patent No. 1,872,- 759, and the above is a summary of the description given there.

In the operation of the above type of cleaner on a downlow lter, a localized area of agitation is created in the sand of the iilter by the solenoid 2I, or by a corresponding mechanical or In the modification shown, the solenoid 2I is intermittentlyv energized by a direct current, or an alternating current of relatively low frequency ispassed through it. This causes the magnetite of the filter bed to be picked up, held for a fraction of a second, andy then dropped back upon the screen.

In the localized area of agitation such as that existing under the electromagnet the sand of the lter offers a greatly reduced resistance to the passage of water therethrough and a stream of wash water is therefore drawn in from the effluent side of the lter. This wash water collects the dirt and impurities which have been released from the sand by reason of the agitation in the same way that the dirt is collected by the streams of water from hydraulic agitators. In both cases, the resulting suspension of dirty water is drawn in through the neck 20 and overflows the Weir I.'I into the chamber I6, from which it is continuously discharged by the pump IGa By proper adjustment of the weir plate I'I the current of wash water entering through the area of agitation can be so, regulated as to remove substantially all the `dirt from the sand and this regulation can be Weir in the outlet passage of the lter to adjust the eilluent level of the filtered liquid.

. It is apparent from the above description that the eiiicient operation of the cleaner results from the upward flow of currents of water through a localized area of the iilter in which the sand is so agitated as to oier little resistance thereto.

Experience has shown, however, that dirty wash l .its downward passage. l Comparative tests have shown that the illtered eilluent may contain as much as 50 parts per million of additional solids when such a cleaner is in operation.

'I'he present inventionovercomes this source of contamination of the eflluent by providing a sealing plate 30 which, in the normal operation of the cleaner tank, is embedded in the sand of the filter directly under the area of agitation and compensates for the increased permeability of the lter therein. This sealing plate 30 consists of a thinhorizontal 'sheet of metal having sharpened edges 3l and upturned ends 32 which are attached to the side walls I2 of the caisson,

as by nuts and bolts 33, directly under the agitator 2|. It travels through the sand of the lter just above the screen 6 and directly under the area of agitation created by the electromagnet, and operates to baille or deflect any direct flow of water through the area of agitation and cause it to flow laterally through the lter bed and thus follow a path through the sand thereof. This ilters out the dirt and impurities contained in the wash water and prevents their admixture with the filtered eilluent.

'I'he operation of the sealing plate 30 will be illustrated with reference to the operation of the solenoid 2I, in conjunction with which it is shown. When the electromagnet is energized, the magnetite sand of the filter is churned up and held for a fraction of a second, during which time the dirty water contained in the caisson has an opportunity to flow directly downwardly onto the screenr. The plate 30 bailles this direct ilow, and turns the liquid aside so that it must pass laterally through the undisturbed portion of the illter bed which holds back the impurities contained in the water.

The width of the plate 30 with respect to the vagitator 2I is an important feature of the invention. It will be apparent that the plate 30, while limiting the undesired passage of dirty water downwardly through the area of agitation, can also limit to a certain extent the upward ow of wash water on which the eflicient operation of an electromagnetic cleaner must depend. Accordingly, the plate 30 must not be found that the most eilicient sealing plate is one having an effective width which is substantially the width of the open core 22 of the solenoid 2I, since this core constitutes an open channel or passage for the direct downward ow of water through the area of lessened resistance under it. Accordingly, the combination of a solenoid having an open core with a sealing plate directly This is pardiblb `oi? said solenoid and under the open core and of the same width constitutes a further speciiic feature of the invention.

While the invention has been described in detail in conjunction'with a speciilc modification thereof, which accomplishes the objects of the invention in a new and improved manner, it should be understood that in its broader aspects v'the invention is not limited to the details shown.

On the contrary, substitutions and modications of the apparatus shown may be resorted to. with- -in the scope of the appended claims.

What I claim is:

1. A clarification filter of the dow'now type comprising in combination a lter including a filter bed support, a relatively thin filter bed of sand on said support, a liquid inlet above and a liquid outlet passage below said illter bed, and a cleaning devicev comprising a cleaner caisson means to move the same over said lter bed, an agitator carried. by said cleaner for creating a localized area of agitation in the sand of the filter, a chamber within said caisson for receiving wash water from the area of agitation, means for discharging wash water from said chamber, and a -sealing plate attached to said cleaner mechanism and located immediately beneath the area vof agitation and having substantially its entire bottom surface in contact with the filter bed material.

2. A clariiication illter of the'downflow type comprising in4 combination a iilter including a filter bed support, a filter bed of magnetic sand on said support, a liquid inlet above and a liquid outlet passage below said illter bed. and a cleaning device comprising a movable cleaner carrying a solenoid adjacent the filter bed', said solenoid having a hollow core, and a sealing plate carrier by said cleaner directly under the hollow surface in contact with the material oi' having substantially its entire bottom surface in contact with the filter bed material.

3. A clarification iilter of the downilow type comprising in combination a lter including a lter bed support, a filter bed of magnetic sand on said support, a liquid inlet above anda liquid .outlet passage below said iilter bed, and a cleaning device comprising a moveable cleaner carrying a solenoid adjacent the filter bed, said solenoid having a hollow core, and a sealing plate of a width substantially equal to the width of said core carried by said cleaner directly under the core and having substantially its entire bottom surface in contact with the iilter bed material.

4. In combination, a illter hed, means to flow 'influent to be filtered on top of the bed, means to remove clean eiiiuent from'beneath the bed,amov able cleaner adapted totravel over the lter bed and means to move the cleaner over the bed, said cleaner including means for'creating a zone of agitation in the lter bed material at a localized area whereby dirt held by the bed material is washed therefrom into the water in and around said zone, meansto remove the wash water from said zone, and a plate supported by the movable cleaner and movable therewith, extending sub' stantially in a horizontal plane immediately beneath the zone of agitation and substantially at i the bottom thereof to baille the ilow of dirty water through the bed at that point.

5. The combination of claim 4 in which the plate is of appreciable width in the direction of its travel and has substantially its entire lower the ltei bed.

- WILLIAM C. LAUGHLIN. 

